Case Study Comparing Effects of Microplastic Derived from Bottle Caps Collected in Two Cities on Triticum aestivum (Wheat)

Abstract

As plastic has become an integral component of daily life, microplastic has become a ubiquitous, unavoidable constituent of nearly all ecosystems. Besides monitoring the amount and distribution of microplastic in the environment, it is necessary to understand the possible direct effects, especially toxicity and how it is affected by environmental factors where it is discarded. The present study investigated how microplastic derived from high-density polyethylene bottle caps collected in two climatically different cities, i.e., Singapore (tropical rainforest climate) and Lahti, Finland (continental climate), affected the essential agricultural grain crop, Triticum aestivum (L.). Wheat seedlings were exposed to microplastic derived from these collected bottle caps, as well as new and artificially aged caps, for seven days. Morphological parameters, such as root and shoot length and oxidative stress development, were measured. Exposure to microplastic derived from the caps resulted in reduced seedling root and shoot lengths compared to the controls, as well as enhanced lipid peroxidation and catalase activity. With all parameters tested, microplastic derived from Lahti bottle caps exhibited more severe effects than Singapore, which was similar to that elicited by new microplastic. The Singapore microplastic had possibly leached its toxic substances before collection due to accelerated degradation promoted by the prevailing warmer climate conditions.

Lolium multiflorum germination and growth affected by virgin, naturally, and artificially aged high-density polyethylene microplastic and leachates

“…The difference between new and aged MP and leachates indicates that aging drastically decreases the toxicological effect on root and shoot growth. Again, the findings agree with studies by Pflugmacher et al (2020b); Pflugmacher et al (2021a); Pflugmacher et al (2021b), showing that the reduction in phytotoxicity was directly related to aging.…”

“…The authors similarly hypothesized that the toxicological effects may be attributed to leached chemicals. Pflugmacher et al (2021a) showed that climate affected the phytotoxicity of MP, where MP from HDPE bottle caps collected from a cooler climate caused a higher percentage of inhibition on Triticum aestivum (wheat) growth compared to MP from caps collected from a warmer climate. The authors postulated that inherently toxic chemicals had already been prompted to leach out of the MP, accelerated by the ambient conditions, into the environment from where it was collected.…”

“…Previously, Boots et al (2019) exposed Lolium perenne (perennial ryegrass) to HDPE, causing negative growth and development effects. The studies by Pflugmacher et al (2020b) and Pflugmacher et al (2021a) highlighted that the effects of aging should also not be neglected when assessing the adverse toxicological effects of MPs. Furthermore, the need to consider more relevant exposure materials and not just virgin primary MPs to assess risks was also noted.…”

Effects of polypropylene, polyvinyl chloride, polyethylene terephthalate, polyurethane, high-density polyethylene, and polystyrene microplastic on Nelumbo nucifera (Lotus) in water and sediment

“…Setälä et al ( 2014 ) reported that MP could enter the food chain via ingestion and transferred from one trophic level to the next. Various severely toxic effects have been attributed to MP exposure as well as their leachates in different organisms tested (Pflugmacher et al 2020a , 2021a , b ), but not all (Scopetani et al 2020a ). The presence of MPs also has been reported to disrupt the residence of natural biota and thus could potentially influence biodiversity (Pflugmacher et al 2020b ).…”

“…The effects of the six most commonly utilised plastics, PP, PVC, polyurethane (PUR), PET, high-density polyethylene (HDPE), and expanded polystyrene (EPS), were assessed as MP (4-mm diameter particles) on the morphology (germination and growth) and physiology (antioxidative enzyme activities of catalase and glutathione S-transferase) of N. nucifera . Several factors have been shown to influence the toxicity of MP, including the concentration, shape, environmental ageing and climate of the location where it is discarded (Ziajahromi et al 2017 ; Qiao et al 2019 ; Pflugmacher et al, 2020a , 2021a , b ). However, the focus of this study was to investigate the toxic effects of possible leached chemicals from various polymer types, thus selecting a larger particle size and avoiding media turbulence to assure that any adverse effects observed were not due to uptake.…”